Generally, display devices display two-dimensional images. Recently, as the demand for three-dimensional images increases in the fields, such as games or movies, and the like, display devices displaying three-dimensional images have been developed. A pair of two-dimensional images is input into two eyes of an observer, and the input images are merged in the brain of the observer, thereby recognizing a three-dimensional image.
Stereoscopic display devices (hereinafter, referred to as 3D devices) may be classified into a stereo-scopic type and an auto stereo-scopic type according to whether an observer needs to wear special glasses. In auto stereo-scopic devices, a parallex barrier method described in Patent Document 1 or a lenticular lens method described in Patent Document 2, and the like are usually used.